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Topic Review (Newest First)

01-04-2010 05:29 AM

Crosley

this makes me wonder what numbers on what tag of this trnas you were reading. In your first post , you indicated that the trans was a 1991 vette unit and the numbers match that idea.

It would be good to know what to look for correctly on the next core to avoid another older unit. I've seen some 1991 - 92 -93 trans cases without the rainbow cast line on them

I would suggest another -newer core. the valve body calibrations are better - easier to work with on the 1988 - 1992 units..

01-04-2010 04:00 AM

123pugsy

Get one 1988 and up.

Easy to spot.

Look for the "rainbow" casting flash on the passenger side.

01-03-2010 08:41 PM

qwkswede

Dang. I also see that I don't have the auxillary valve body on this transmission. Should have changed the title of this thread to "What year is this transmission?" And since I didn't even know what I'm looking at until I read about it here or in the manual, I'm not quite sure what to do with this core I have on my hands. It doesn't really match my rebuild kit. And I think its prudent to have the later model improved parts that GM installed. I need a strong transmission for this project. I basically have an early 87 trans housed in a 1991 case.

So should I hunt around for a new core that really has the later model internals?

Or is it pretty straightforward to add the good later model parts to this older core. I see that this is starting to add alot of cost to my otherwise budget transmisison build.

If I decide to upgarde all the weaker internal parts I need to know whats necessary to track down. Here is a list I came up with. This is just me going through the ATSG guide. Can you guys let me know if this is close to the right list of upgrade parts?

1. Need 88+ wider center support for low reverse roller clutch. ($20, on the way)
2. Need 88+ valve body
3. Need 88+ auxillary valve body.
4. Need 88+ reverse input drum and piston. ($99 new?
5. Need 88+ pump ???? Maybe? I have a late model stator shaft in the rebuild kit. Does swapping this bring the pump up to date?
6. Need some selective shims to make all these assembled parts and clutches work right and have correct spacing..

01-03-2010 05:29 PM

qwkswede

Quote:

Originally Posted by Crosley

A suggestion I have used a few decades:

set the low - reverse clutch pack into the case dry... no planetary unit or other items in the way. Set it up eggzackly how it will operate in the trans. No roller clutch , no race , nothing to get in your way

Set the center support in place , look through the bottom of the case at the clearance. there is an opening there...

A long time accepted clearance for double sided frictions and flat steel plate is .010 per friction. 5 frictions would be .050 clearance.

If you have compressed air ... install the snap ring for the center support and test the apply through both ports

Good to know.
It looks like I have about 90-100 thou clearance in the low/reverse pack looking through the slot in the bottom. I'll check it again when I get the new center support. I understand it will change. But if it doesn't I will need to find some different thickness selective plates. I'll talk to Dana at Pro-built about getting some different plates to set the clearance correctly. Is there a problem running the clutches on the loose side?

I did find another part that is interestingly misplaced. The reverse input drum matches the description of the early 1987 variety according to the manual. And the oil pump has the smaller hole size between the seals that indicates 1987 model. Wierd. The entire insides of this transmission seem to be the early style. The reverse input drum has the checkball capsule in it, and it also uses the steel piston inside.

I haven't looked at the valvebody closely yet. I wonder if I wll see some early model parts here too.

01-03-2010 11:39 AM

Crosley

A suggestion I have used a few decades:

set the low - reverse clutch pack into the case dry... no planetary unit or other items in the way. Set it up eggzackly how it will operate in the trans. No roller clutch , no race , nothing to get in your way

Set the center support in place , look through the bottom of the case at the clearance. there is an opening there...

A long time accepted clearance for double sided frictions and flat steel plate is .010 per friction. 5 frictions would be .050 clearance.

If you have compressed air ... install the snap ring for the center support and test the apply through both ports

01-03-2010 10:31 AM

S10xGN

Can't help you with Q #1, but yes, always soak the frictions before assembly, and buy the proper assembly lube, it's much stickier than vaseline which helps in certain circumstances...

Russ

01-03-2010 10:23 AM

qwkswede

OK, there are a couple things that the ATSG guide seems to skip.

I have a dimension for the stack height of 1.200 - 1.240". But I don't see a clearance spec in the ATSG manual. Penny thickness looks to be about .060-.065". Is that about right?

Also, is soaking the frictions in ATF before assembly the recommended treatment?

And one more Q. Vaseline is appropriate for assembly lube on the bearings, bushings, and rubber parts?

01-03-2010 05:00 AM

123pugsy

Like Crosley mentioned, check your clutch pack clearance.
The manual will tell you to measure the stack up and such but I found a nice tip online somewhere whereby you can use some pennys or dimes on top of the clutch pack and drop in the center support to check the clearance.

I usually do this before installing the reaction gear and carrier.

01-02-2010 10:25 PM

qwkswede

[QUOTE=mmerlinn]You can't put the wider sprag in the narrow housing. You must change both.[/QUOTE

Yes, thats why I bought the wider center support housing. I actually got the used inner race, and a sprag too. I don't know why the narrow one was in this 1991 transmision, but I had bought parts assuming a 91 model, and was a bit confused when it had some unusual parts inside.

01-02-2010 09:52 PM

mmerlinn

Quote:

Originally Posted by qwkswede

Well, today I bought the later wide center support online, found an ebay auction. And I found the details of the different clutch stackups in the ATSG manual. I think I can sort that out no problem. Thanks for the help.

You can't put the wider sprag in the narrow housing. You must change both.

01-02-2010 07:01 PM

qwkswede

Well, today I bought the later wide center support online, found an ebay auction. And I found the details of the different clutch stackups in the ATSG manual. I think I can sort that out no problem. Thanks for the help.

01-02-2010 11:56 AM

Crosley

I've seen many late cores with early parts inside.

the center support for the wide roller clutch will fit back in place.. you MUST watch the low-reverse clutch pack clearance.

there was also a thicker flat plate with 4 standard flat steel plates used with the waved cushion plate.

01-02-2010 10:25 AM

qwkswede

It is definitely a corvette case. Thats fine with me, it is going into a volvo with a fabricated cross member. I can work with the vette style mounts. I would have preferred that tje trans was untouched and original for my first rebuild. I dont really need unexpected combos to confuse me right now. I wonder what wierd mix match parts i will find. Since it seems that someone retrofitted the th350 roller clutch assembly i assume they are interchangeable? I want the stronger one. I will do some calling to see about buying the later style carrier.

01-02-2010 09:18 AM

123pugsy

Quote:

Originally Posted by qwkswede

It is supposedly from a 91 corvette. And the serial numbers on the tag match that assumption. Seems wierd huh?

I was trying to figure out if it had ever been rebuilt before. The case has a layer of paint that seems pretty old and is peeling. Did they get paint at the factory?

No paint from the factory.

01-02-2010 09:14 AM

Crosley

Quote:

Originally Posted by qwkswede

It is supposedly from a 91 corvette. And the serial numbers on the tag match that assumption. Seems wierd huh?

I was trying to figure out if it had ever been rebuilt before. The case has a layer of paint that seems pretty old and is peeling. Did they get paint at the factory?

a 1991 corvette case will not have a trans mount area on the main case near the rear... 2 bolt holes normally there are NOT on a vette case.

the wide roller clutch is late design for 700r4 4l60 trans.

early narrow roller clutch is same as a t-350 design.

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